Technical Field
The present invention relates to a plasma source for a plasma CVD apparatus and a manufacturing method of an article using the plasma source.
Description of Related Art
A plasma-enhanced chemical vapor deposition (CVD) technique (Plasma-enhanced chemical vapor deposition: PECVD) is a kind of a chemical vapor deposition (CVD) technique that can deposit a film of various materials on a processing surface by using plasma. The plasma CVD technique is widely used for manufacturing, for example, semiconductor elements.
A plasma-enhanced chemical vapor deposition (CVD) apparatus used for such a plasma CVD technique is equipped with a plasma source that generates plasma. Normally, the plasma source includes a pair of electrodes connected to a high-frequency AC power supply with a frequency such as, for example, 13.56 MHz, and when a discharge is started between the electrodes by the high-frequency AC power supply, plasma is formed between the electrodes. In this state, when a source gas is supplied into the plasma, atoms and/or molecules of the source gas are exited and made to be chemically active, and, thereby, a chemical reaction occurs at a surface to be processed, which permits a film of an object substance being deposited on the surface to be processed.
Recently, in order to permit a large-area film deposition, a plasma source equipped with a low-frequency AC power supply of, for example, the order of kHz, instead of the high-frequency AC power supply, has also been developed. Japanese Translation of PCT International Application Publication No. 2011-530155 discloses that, in a case where such a plasma source is used, plasma having a sufficient length can be provided stably.
As described above, a plasma source that can stably provide plasma having a sufficient length is disclosed in the above-mentioned patent document.
However, in the plasma source of the structure such as disclosed in the above-mentioned patent document, the plasma density of the plasma generated in the vicinity of the electrodes is not sufficient. Accordingly, the reactivity of the source gas supplied to a plasma area in the vicinity of the electrodes becomes low, and there may be a case where a film cannot be deposited on the surface to be processed at a sufficient film-deposition rate.